WASHINGTON — Some of the Canada geese that were rescued from a Potomac River oil spill earlier this month returned to the wild Monday.

When mineral oil from a Dominion Power substation in Crystal City, Virginia, made its way into the Potomac River near Roaches Run Waterfowl Sanctuary in early February, dozens of birds became coated in oil. Tri-State Bird Rescue & Research rounded up the birds and released 21 of them in Belle Haven, Virginia, Monday — close to where the birds were found.

Tri-State Bird Rescue & Research Coordinator Michelle Neef says the location of the release was important.

“Because some of them can be territorial, some do migrate, some have partners that they do want to be with,” Neef says.

Eleven birds — including two mallards — are still undergoing rehabilitation and will be released at a later date.

The Coast Guard said 29 birds in total died as a result of the spill.

Earlier this month, Dominion Power accepted full responsibility for the oil sheen on the river, and will likely have to foot the bill for its cleanup.

WTOP’s Sarah Beth Hensley contributed to this report.

Editor’s note: This story has been updated to reflect a change in the number of bird deaths.